Hitherto, the refuse treating apparatus is classified into the combustion heat method, microwave method and electric heater method, by the type of heating source. The refuse treating apparatus of combustion heat method employs gas fuel or liquid fuel, and the entire apparatus is large and complicated, and involves a safety problem. The refuse treating apparatus of microwave method is suited to drying process of moist waste because the microwaves are selectively adsorbed in the moisture in the waste, but is slightly inferior in safety and controllability. As compared with them, the refuse treating apparatus of electric heater method is excellent in safety and controllability, and is small in size, and hence the cost can be reduced.
However, in the conventional refuse treating apparatus employing electric heaters, when heating the refuse by the heater, in order to generate steam from the refuse, the heater surrounding temperature must be set over 100.degree. C. to obtain overheated steam, and when continued to heat in this state, if drying is over, the temperature change is small (nearly same as the heater set temperature), and it is hard to detect the drying end time. If the drying end time is not detected accurately, drying time becomes longer, and the heating cost is wasteful, or the refuse is scorched, which is not sanitary.